Gas turbine engines are used to power aircraft, watercraft, power generators, and the like. Gas turbine engines typically include a compressor, a combustor, and a turbine. The compressor compresses air drawn into the engine and delivers high pressure air to the combustor. In the combustor, fuel is mixed with the high pressure air and is ignited. Products of the combustion reaction in the combustor are directed into the turbine where work is extracted to drive the compressor and, sometimes, an output shaft. Left-over products of the combustion are exhausted out of the turbine and may provide thrust in some applications.
Compressors and turbines typically include alternating stages of static vane assemblies and rotating wheel assemblies that perform work on or extract work from gasses moving through a primary gas path of the engine. The rotating wheel assemblies include disks carrying blades around their outer edges. When the rotating wheel assemblies turn, tips of the blades move along blade tracks that are arranged around the rotating wheel assemblies. Such blade tracks are adapted to reduce the leakage of gas over the blades without interaction with the blades. The blade tracks may also be designed to minimize leakage of gas into or out of the primary gas path.